Apparatus for flaring pipe liners

ABSTRACT

An apparatus for flaring the end of a thermoplastic liner installed in a metal pipe. The end extends beyond the pipe and the pipe having at least one flange mounted thereon. The apparatus includes a first forming head having a liner contacting surface disposed at an acute angle relative to said liner, said surface being adapted to be pushed against said end to cause said end to flare outwardly about an acute angle and a second forming head having a liner contacting surface being disposed at an angle of at least ninety degrees relative to said liner. The second forming head is adapted to be pushed against said end to cause said end to bend into contact with said flange.

BACKGROUND OF THE INVENTION

This invention relates to a method and apparatus for flaring an end of aplastic pipe liner installed inside a pipe.

It is known to line metal pipes with plastic liners to rehabilitate themand/or to provide corrosion or chemical resistance. There are manydifferent methods of lining pipe known in the art. Canadian patent No.1,241,262 (Du Pont Canada Inc.) discloses a method and apparatus forlining pipe which involves taking a liner of a larger O.D. than the I.D.of the pipe to be lined, reducing the diameter of the liner with drivenrollers and pulling the liner into the pipe. The pulling force is thenreleased and the liner is allowed to expand and fit tightly against thewall of the pipe.

It is known to weld plastic flanges to the ends of the liner afterinstallation so that liner segments may be joined together. However, itis difficult to do this after the liner has been inserted into a pipe.

U.S. Pat. Nos. 4,383,966 (Svetlik) and 4,156,710 Caroll et al) bothteach the idea of flaring thermoplastic pipe ends to form flangesthereon. However, neither of these patents teach a method of carryingthis out on a thermoplastic liner installed inside a pipe.

U.S. Pat. No. 3,341,894 (Flaming) teaches the idea of flaring the end ofa liner installed inside a pipe by using a heated plug. It has beenfound that using a single plug of the design disclosed in this patentcauses the end of the liner to curl under itself.

U.S. Pat. No. 4,525,319 (Kaspe) discloses a method and apparatus forforming a flange on a thermoplastic pipe inside a sleeve. The inventionemploys only a single head to move the end of the liner through anobtuse angle to form a flange. This head may cause the liner to buckleor it may cause the liner to curl under itself, which in either casewill create an unsatisfactory flange.

It is desirable to flare the end of the liner after it has beeninstalled in a pipe to form a flared end while inhibiting buckling orcurling of the liner under itself.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides an apparatus for flaring theend of a thermoplastic liner installed in a metal pipe, said endextending beyond the pipe and said pipe having at least one flangemounted thereon, said apparatus comprising:

a first forming head having a liner contacting surface disposed at anacute angle relative to said liner, said surface being adapted to bepushed against said end to cause said end to flare outwardly about anacute angle; and

a second forming head having a liner contacting surface being disposedat an angle of at least ninety degrees relative to said liner, saidsecond forming head being adapted to be pushed against said end to causesaid end to bend into contact with said flange.

In another one of its aspects, the invention provides a method forflaring the end of a thermoplastic liner installed in a metal pipe, saidend extending beyond the pipe and said pipe having at least one flangemounted thereon, said method comprising:

pushing against said end with a first forming head and applying heat tocause said end to flare outwardly about an acute angle; and

subsequently pushing against said end with a second forming head andapplying heat to cause said end to bend into contact with said flange.

It has been found that the use of the second forming head allows theliner to be bent gradually into contact with the flange so that theliner is inhibited from buckling or curling under itself.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the invention will be further described, by wayof illustration only, with reference to the following drawings, inwhich:

FIG. 1 is a side view of a partially assembled apparatus for flaringpipe;

FIG. 2 is a side view in partial cross section of a flaring headassembly for use with the apparatus of FIG. 1;

FIG. 3 is a side view in partial cross-section of the apparatus of FIG.1 during a first flaring stage;

FIG. 4 is a side view in partial cross-section of the apparatus of FIG.1 during a second flaring stage;

FIG. 5 is a side cross-sectional view of the apparatus of FIG. 1 duringa third flaring stage; and

FIG. 6 is a side cross-sectional view of the apparatus of FIG. 1 afterthe third flaring stage.

A partially assembled apparatus for flaring a thermoplastic liner 10installed inside a metal pipe 12 having a flange 14 on its end isillustrated in FIG. 1. The liner 10 is held in position in the pipe by aretractable anchor 16 (indicated in ghost outline), the design of whichis known in the art. The end 18 of the liner extends beyond the end ofthe pipe flange 14 by an amount sufficient to cover the raised face 19of the flange 14 after flaring. A flaring unit for flaring the end ofthis liner is generally indicated by the number 22. This flaring unit 22is pushed against the liner by a hydraulic cylinder assembly 24. A thirdflaring head 26 also forms part of the apparatus and method as will bediscussed later.

Details of the flaring unit 22 may be seen in FIG. 2. This apparatuscomprises a heating plate 28 having a handle 30 on the side and aflaring head 34, 36 mounted on each of the circular heat transfersurfaces 32 thereof. A first flaring head 34 has a generally convexexternal surface 38. The slope of the peripheral portion 39 of thissurface is about 30 degrees. A second flaring head 36 also has agenerally convex external surface 40. The peripheral portion 42 of thissurface is flat. The flaring heads 34, 36 each have a recess 44 at thecentre thereof for receiving a projection 46 of the hydraulic cylinderassembly 24 (see FIG. 1).

The projection is located on the end of a hydraulic cylinder 48, as maybe seen in FIG. 1. This cylinder 48 is located in a sleeve 50 and theannulus between the cylinder and the sleeve is sealed and filled withhydraulic fluid via an inlet 52. This sleeve 50 is attached to a secondflange 54. This second flange 54 is bolted to the pipe flange 14 so thatit is coaxial with the pipe 12.

The third flaring head 26 is of the same design as the second flaringhead 36 described above except that it has a recess 56 on its rear face58 instead of on its front face 60.

The operation of the preferred embodiment of the invention will now bedescribed with reference to FIGS. 3, 4 and 5. As may be seen in FIG. 3,the projection 46 of the hydraulic cylinder assembly 24 is firstreceived in the recess 44 of the second flaring head 36. The heater 28is then turned on so that the flaring heads 34, 36 are heated to atemperature around the glass transition temperature of the linermaterial. The first flaring head 34 is then pressed against the linerusing the hydraulic cylinder assembly 24 for a suffient amount of timeand at a sufficient pressure so that the peripheral portion 39 contactsand flares the liner end 18. The liner end 18 is thereby flared by abouta sixty degree angle. The first flaring head 36 is then removed from theliner and the flaring unit is turned over by turning the handle 30 sothat the second flaring head 36 faces the liner. The projection 46 ofthe hydraulic cylinder assembly is then inserted in the recess 44 of thefirst flaring head as may be seen in FIG. 4. The second flaring head 36is then pressed against the partially flared end 18 using the hydrauliccylinder assembly 24. The peripheral flat portion 42 of the head ispressed for a sufficient amount of time and at a sufficient pressure tobend the flared end 18 until it is normal to the rest of the liner andis in contact with the raised face 19 of the flange 14.

The flaring assembly 22 is then removed from the liner and is disengagedfrom the hydraulic cylinder assembly 24. The third flaring head 26,which has been chilled in a refrigeration unit, is then mounted on thehydraulic cylinder assembly 24 by inserting the projection 46 of thehydraulic cylinder assembly into the recess 56 on the rear face 58 ofthe head 26. The third flaring head 26 is then pressed against the linerend 18 for a sufficient amount of time to cool the liner whilemaintaining it in the bent shape.

The third head is removed after cooling and, as may be seen in FIG. 6, aretaining plate 62 may be bolted to the flange 14 to inhibit the linerend from creeping back to its original unflared position.

Modifications to the preferred embodiment may be made within the scopeof the invention as described and claimed. The periphery of the firsthead may be of any design suitable to flare the end of the liner aboutan angle in the range of about 30 and 80 degrees and most preferablyabout an angle of around 60 degrees relative to the rest of the liner.

The second head may be of any design suitable to flare the end of theliner by about an angle of between 90 and 110 degrees and mostpreferably about an angle of around 90 degrees relative to the rest ofthe liner.

The preferred embodiment of the present invention provides severaladvantages. The use of the first two heads allows for gradual forming ofthe flared end to avoid buckling or curling under of the end. Also, thetwo heads are mounted on opposed heated plates of a heater to form aunit that is easy to use and allows the heads to be quickly and easilyinterchanged. The cooled head allows the flared end to be cooled quicklywhile it is maintained in the flared position. The use of a finalretaining plate during storage inhibits creep of the liner back to itsoriginal unflared position.

I claim:
 1. An apparatus for flaring the end of a thermoplastic linerinstalled in a metal pipe, said end extending beyond the pipe and saidpipe having at least one flange mounted thereon, said apparatuscomprising:a first forming head having a liner contacting surfacedisposed at an acute angle relative to said liner, said surface beingadapted to be pushed against said end to cause said end to flareoutwardly about an acute angle; a second forming head having a linercontacting surface being disposed at an angle of at least ninety degreesrelative to said liner, said second forming head being adapted to bepushed against said end to cause said end to bend into contact with saidflange; and a pressure application means for alternately pushing saidheads against said liner end.
 2. The apparatus of claim 1 wherein theliner contacting surface of the first head is disposed at an angle inthe range of about 30 and 80 degrees relative to said liner.
 3. Theapparatus of claim 1 wherein the liner contacting surface of the firsthead is disposed at an angle of about 60 degrees relative to the rest ofthe liner.
 4. The apparatus of claim 1 wherein the liner contactingsurface of the second head is disposed at an angle of about 90 degreesrelative to the rest of the liner.
 5. The apparatus of claim 1 furthercomprising a heater plate for heating the forming heads and wherein eachof the forming heads is mounted on a respective side of said heaterplate.
 6. The apparatus of claim 1 further comprising a third forminghead having a liner contacting surface which is disposed at an angle ofat least ninety degrees relative to said liner, said third forming headbeing adapted to be pushed against said end to cool said end after ithas been contacted with said second forming head.
 7. The apparatus ofclaim 1 further comprising a retaining plate adapted to be attached tosaid flange for retaining said end in a bent position after it has beenbent by said second forming head.
 8. The apparatus of claim 5 whereinsaid first and second heads each have mounting means located thereon forremovably mounting said heads onto said pressure application means forpushing said heads against said liner.
 9. The apparatus of claim 1wherein said pressure application means is a hydraulic cylinderassembly.
 10. The apparatus of claim 8 wherein said mounting means is arecess and wherein a projecting portion on the end of said pressureapplication means is locatable in said recess.